1. Field of the Invention
The present invention relates to the connection between motive means and the lance of a soot blower with which the lance is rotated and reciprocated in carrying out its function of cleaning furnace tubes with a spray of steam, or other cleaning fluid. More specifically, the present invention relates to rotation of a lance of square cross section and reciprocation of the lance as the lance is connected to a carriage within a housing, the reciprocation motivated through a rack on the housing and a pinion on the carriage.
2. Description of the Prior Art
Combustion of fuels in a utility boiler produces huge amounts of particulate matter which accumulates on heated surfaces and reduces the heat transfer from the combustion to liquids to be vaporized. Coal firing is very productive of particulate matter, be it in the form of soot and/or slag. The lower the quality of coal, the more quickly is the accumulation of particulate matter on surfaces heated by the combustion. Removing structure must be frequently inserted into the furnace space to shear away the accumulations which are the enemies of heat transfer.
Enter the lowly soot blower. Essentially, the soot blower is a pipe, with a nozzle at its end, inserted into a hole in the wall of the furnace. Steam, or other vapor, is fed into the tube and ejected from its nozzle with great force. Correctly directed, this vapor-belching tube can effectively shear particulate matter from large areas of the heated surfaces.
In the huge, multi-storied utility boiler, it is not uncommon to supply up to 100 soot blowers. Rows of these blowers are poised at their furnace openings, the rows being on the order of vertical 8' centers. Further, the blowers are rolled into the furnace under elaborate programs to sequentially cut at the accumulations on the heating surfaces and maintain the efficiency of heat transfer from the combustion process to the vaporizable liquid behind the heating surfaces.
The environment in which the soot blower operates is inherently dirty. Coal dust in the atmosphere about a boiler is an unavoidable fact of the life of this tool. This dirt is an enemy to the mechanical system between the electric motive means and the soot blower with which the electric motive means rotates and reciprocates the soot blower lance.
Another point of vulnerability is the packing gland seal by which the cleaning vapor is retained within the lance. Although other vapors could be employed, by and large high pressure steam is the most available cleaning medium. The steam is conducted to each blower through a feed tube and the outer casing of the lance is rotated and reciprocated over a substantial length of the feed tube. Obviously, some form of seal between the outer surface of the feed tube and the inner surface of the outer casing of the lance is necessary to contain the cleaning medium and force it from a nozzle mounted on the forward end of the casing. The seal must be protected from heat and mechanical stress if reasonable life is to be expected. Thus, under the environment about the utility boiler, which is hostile to mechanical motion and sealing, are the problems of dirt isolation to preserve efficient articulation of the parts of the blower which must move relative to each other.